hardpan

名词 hardpan:

1. crust or layer of hard subsoil encrusted with calcium-carbonate occurring in arid or semiarid regions
   同义词：caliche

hard.pan

n.（名词）
A layer of hard subsoil or clay.Also called caliche
硬质地层也作 caliche
Hard, unbroken ground.
硬地
A foundation; bedrock.
坚固的基础；基本事实